What is OZCHRON?

• Introduction
• Review and Redevelopment
• What's in OZCHRON
• Geochronological data
• Publication data
• Full laboratory data
• Accessing the data in OZCHRON

Introduction

OZCHRON is a database of Australian geochronological data managed and maintained by Geoscience Australia.

Geoscience Australia has operated the OZCHRON database since 1993. The database is a compilation of geochronological information on Australian Precambrian and Phanerozoic terranes. The data in OZCHRON have been compiled from a variety of published and unpublished sources. All new geochronology done by Geoscience Australia geochronologists is entered into OZCHRON along with ages compiled by Geoscience Australia projects from published data in specific study areas.

Review and Redevelopment

The management of geochronology data at Geoscience Australia is currently under review and new systems are being developed during 2007/08 and beyond. During this time some previously available data delivery mechanisms will be disabled. In most cases, delivery of existing data holdings will continue via alternate means such as Comma-Separated Value (CSV) files.

It is important to note that although data delivery tools have been disabled, the OZCHRON database will remain intact and available for specific queries as required by Geoscience Australia clients.

For further information about the geochronology data management redevelopment project, or access to existing data contact the Geochronology Data Custodian.

What's in OZCHRON

The geochronology methods currently accommodated in OZCHRON are:

• SHRIMP U-Pb (Sensitive High Resolution Ion Microprobe),
• Ar-Ar,
• Sm-Nd.
• Conventional U-Pb pooled ages,
• Rb-Sr.
• K-Ar,

For each dating method OZCHRON summarises the analytical data and resulting pooled and interpretive ages and acknowledges the primary source of the data. Comments also are included on the geological relevance and reliability of those ages. In addition to the Sensitive High Resolution Ion MicroProbe (SHRIMP) dating method, provision has been made for capturing and storing raw machine data and the primary processed data.

All samples in OZCHRON are spatially located and record the lithology, geological unit and, in many cases, additional information such as degree of metamorphism or alteration, mineralogy and grainsize.

Geochronological data

The geochronological data includes raw machine data, processed data, pooled results and interpreted ages. For most methods in OZCHRON only the processed data, pooled results and interpreted ages are stored as well as metadata on the standards used and the data reduction methods. Dating with the SHRIMP also has the ability to store the raw data file obtained from the machine and analytical data pertaining to the standards.

Publication data

Typically, geochronological results published in the literature will consist of a subset of processed analytical data and a reasonably comprehensive set of interpretive pooled age results. Limited metadata surrounding the acquisition and processing of the analytical data, and the methodologies used to derive the interpretive pooled ages, are usually provided. It is not uncommon for a publication to merely supply an age and error with minimal metadata (e.g. the dating method and a reference).

Full laboratory data

A full geochronological dataset captured in OZCHRON will consist of the raw data generated by the SHRIMP, the full set of processed data for the unknown and standard analyses and comprehensive interpretive pooled age results. The dataset will have accompanying comments on the results from the author and other interested parties. Extensive metadata surrounding the acquisition, processing and interpretation of the data also are provided.

Accessing the data in OZCHRON

Due to the review and redevelopment process during 2007/08 and beyond, the previous map interface for accessing OZCHRON has been disabled, although the data remains available via:

• Recent reports

  A summary report of recently entered data is available. It contains sample location and descriptive information along with simple pooled interpreted ages for a single sample.

• Comma-Separated Value (CSV) file

  A 'flat' file is available in Comma-Separated Value format. These data consist of sample data and simple, pooled interpreted ages for all data of a particular isotopic method available in OZCHRON.

• Query

  More detailed data for a given sample (e.g. individual analyses) can be extracted from OZCHRON if required by inquiry to Geochronology Data Custodian. Please try to provide as much information as possible such as sample ID.